Carton having stacking strength-enhancing feature

ABSTRACT

A carton has a triangular shaped internal buttress arrangement for enhancing the stacking strength of the carton. The arrangment is formed from the distal portion of at least one of the side end flaps.

REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC § 1.19 (e) to U.S. Provisional Application Ser. No. 60/735,619, filed Nov. 9, 2005, the entirety of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates generally to cartons for use in packaging articles and, more particularly, relates to a carton whose stacking strength is enhanced by a special arrangement of an end closure structure.

BACKGROUND OF THE INVENTION

Cartons are useful for allowing consumers to purchase, transport and store a desired quantity of articles. However, some articles are flexible and/or deformable such as juice pouches. Such articles tend to get easily rearranged and crushed within the carton. Moreover, not all cartons have sufficient strength to physically protect the contents when arranged in a stacked condition. Cartons may tend to break open unintentionally when the cartons are subject to compression. What is needed, therefore, is an improved carton for packaging flexible or deformable articles. The improved carton should have good stacking strength to protect the contents when stored or displayed with like cartons in a stacked condition.

SUMMARY OF THE INVENTION

The present invention provides a carton which utilizes end flaps to increase the structural integrity of the carton while continuing to facilitate easy access to the articles within the carton. Flexible and/or deformable articles such as stand-up pouches may be retained within the carton in an organized manner.

Generally described, top and bottom opposed walls are hingedly interconnected by a pair of side walls to form a tubular body. An end closure structure is provided to at least partially close each end of the tubular body. A buttress arrangement is provided by each end closure structure. Each buttress arrangement is disposed within the interior of the carton and extends vertically between the top and bottom walls to enhance the stacking strength of the carton.

In a preferred embodiment of the invention, each end closure structure may include a pair of side end flaps joined to the side walls respectively. Each side end flap may include a proximal portion hingedly connected to the respective side wall and extending toward the other side wall. Preferably at least one of the side end flaps at each end further includes a distal portion hingedly connected to the respective proximal portion. The distal portion of the one side end flap may extend into the interior of the carton to form the respective buttress arrangement. The other side end flap may also include a distal portion extending into the interior of the carton. The distal portions of the side end flaps of each end closure structure may be disposed to form, in conjunction with its hingedly attached proximal portion, and the adjacent side wall, a tubular structure with a triangular cross section to form the respective buttress arrangement. The distal portion of any side end flap not formed into a triangular cross section may be positioned such that distal portion is disposed between the articles within the carton to serve as a partition. These distal portions extend all the way between the top and bottom walls to be in abutment at their upper and lower ends on the top and bottom walls.

The present invention in a still another aspect provides a carton comprising top and bottom opposed walls hingedly interconnected by a pair of side walls to form a tubular body, an end closure structure for at least partially closing each end of the tubular body, and a buttress arrangement provided by each end closure structure. Each buttress arrangement is disposed within the interior of the carton and extends vertically between the top and bottom walls to enhance the stacking strength of the carton. Each end closure structure comprises a pair of side end flaps joined to the side walls respectively. Each side end flaps of each end closure structure comprises a pair of proximal and distal portions. The proximal portion is hingedly connected to the respective side wall whereas the distal portion in hingedly connected to the respective proximal portion. The proximal portions of the side end flaps extend from the side walls toward each other while the distal portions extending from the respective proximal portions into the interior of the carton. Preferably at least one distal portion at each end is disposed to form in conjunction with its respective proximal portion and the adjacent side wall a triangular tubular buttress arrangement. Each side end flap includes a vertical fold line dividing that side end flap into the distal and proximal portions. The distal portion has a horizontal transverse size greater than that of the proximal portion, and preferably between 1.2 and 1.8 time the horizontal traverse size of the proximal portion.

In a preferred embodiment of this aspect of the invention, each buttress arrangement may be held in place without need for an extra gluing step by using slight pressure from the articles within the carton to maintain the buttress arrangement in the desired triangular cross section. Each distal portion of each buttress arrangement may extend all the way between the top and bottom walls to be in abutment at its upper and lower ends on the top and bottom walls, while the distal ends of the distal portion abut the nearest side wall.

The foregoing has broadly outlined some of the more pertinent aspects and features of the present invention. These should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Other beneficial results can be obtained by applying the dislosed information in a different manner or by modifying the disclosed embodiments. Accordingly, other aspects and a more comprehensive understanding of the invention may be obtained by referring to the detailed description of the exemplary embodiments taken in conjunction with the accompanying drawings, in addition to the scope of the invention defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of one embodiment of a carton of the present invention.

FIG. 2 illustrates a plan view of a blank for forming the carton of FIG. 1.

FIG. 3 illustrates a perspective view of the blank of FIG. 2, showing a first step for loading and erecting the carton, wherein articles are placed on the side walls.

FIG. 4 illustrates a perspective view of the blank of FIG. 3, showing another carton-erecting step wherein the side walls are upwardly moved toward each other from the positions shown in FIG. 3.

FIG. 5 illustrates a perspective view of the blank of FIG. 4, showing a still another carton-erecting step wherein the side walls are moved to the vertical position and the carton is partially erected.

FIG. 6 illustrates a fragmentary cross-sectional view taken along line 6-6 of FIG. 1.

FIGS. 7-9 are perspective views of the blank of FIG. 2, showing different stages of an alternative carton-forming process to assemble the carton of FIG. 1, according to the present invention.

FIG. 10 is a perspective view of a carton of a second embodiment according to the present invention.

FIG. 11 is a plan view of a blank for forming the carton of FIG. 10.

FIGS. 12-14 are perspective views of the blank of FIG. 11, showing differnet stages of a carton-forming process to form the carton of FIG. 10, according to the present invention.

DETAILED DESCRIPTION

Referring now to the drawings in which like numerals indicate like elements throughout the several views, the drawings illustrate exemplary embodiments of cartons 10 (FIG. 1), 12 (FIG. 7), and 13 (FIG. 10 ) of the present invention. In these embodiments, the cartons 10, 12, 13 are designed for packaging and dispensing articles “A” which may be beverage pouches made, for example, of a plastic-aluminum laminated film. An example of such a pouch is disclosed in U.S. Pat. No. 5,927,498 which is hereby included by reference.

Generally described, the cartons are formed from foldable sheet material such as paperboard. Carton 10 shown in FIG. 1 is formed from a single blank 14. The blank 14 is configured as shown in FIG. 2 and includes at least four primary panels for forming the carton 10. The primary panels of the blank 14 are a top wall 24, a first side wall 20, a bottom wall 18 and a second side wall 22. These panels 24, 20, 18 and 22 are hingedly connected in series one to the next along fold lines 30, 32 and 34. The top wall 24 is hingedly connected to the first side wall 20 by fold line 30. The first side wall 20 is then hingedly connected to the bottom wall 18 by fold line 32. The bottom wall 18 is then hingedly connected to the second side wall 22 by fold line 34. Each of the panels 18, 20, 22 and 24 is provided with opposing end flaps that are connected to the respective primary panel along transverse fold lines 36 and 38. Fold lines 36 and 38 each extends substantially the full length of the blank 14.

Still referring to FIG. 2, the opposing end flaps include opposing lower end flaps 52 and 54, opposing upper end flaps 56 and 58 and opposing side end flaps 60, 62; and 64, 66. The end flaps 52, 56, 60 and 64 extend outward from the transverse fold line 36 while the end flaps 54, 58, 62 and 66 extend outward from the transverse fold line 38.

Side end flaps 60, 62 , 64 and 66 include medial fold line 70, 72, 74 and 76, respectively. The medial fold line of each side end flap divides that end flap into a pair of proximal and distal portions 60 a, 60 b; 62 a, 62 b; 64 a, 64 b; and 66 a, 66 b. Preferably, as shown in FIG. 2, the width (or horizontal transverse size) W1 of each of the distal portions 60 b, 62 b, 64 b, and 66 b is greater than the width (or horizontal transverse size) W2 of each of the proximal portions 60 1 , 62 a, 64 a, and 66 a. Stated differently, the distance between transverse fold line 36 or 38 and each medial fold line is less than the distance between that medial fold line and the free end edge of the respective distal portion.

The articles “A” are preferably stand-up pouches which may be deformable and are made from a flexible material such as a plastic-aluminum laminated film. In the empty condition, each article “A” is flat. In the filled condition, each article “A” has a flat bottom and generally rectangular front and rear panels. The front and read panels extend from the bottom into a mutual contacting and sealed relationship at the top of the pouch. The bottom of each pouch is in the form, generally, of a hexagon. Each side wall of each pouch has a generally triangular configuration with its base being at the bottom. Therefore, the bottom of each pouch is considerably wider than the top when viewed from the side.

In order to erect or form the carton 10, the side end flaps 60, 62, 64 and 66 are folded upward along transverse fold lines 36 and 38 as shown in FIG. 3. Side end flaps 60, 62, 64 and 66 are then folded along the medial fold lines 70, 72, 74 and 76 respectively so that the proximal portions 60 1 , 62 a, 64 a and 66 a remain in the vertical positions and the distal portions 60 b, 62 b, 64 b and 66 b extend inwardly of the blank to assume a bracing position wherein each distal portion extends downward at an angle toward the adjacent side wall 20 or 22. Stated differently, each distal portion when in the bracing position extends between the respective proximal portion and the adjacent side wall such that it is disposed obliquely with respect to either the respective proximal portion or the adjacent side wall. Each of the side end flaps thus form part of a tubular corner column having a triangular cross section; each triangular corner column is formed in part from the respective side end flap and in part from a portion of the adjacent side wall.

Alternatively, the corner columns may be completed at the later stage of the carton-forming process. In such an alternative process, the distal portions 60 b, 62 b, 64 b and 66 b may be merely pre-folded along the medial fold line 70, 72, 74 and 76 with respect to the vertically-disposed proximal portions 60 a, 62 a, 64 a 66 a to the extent that the distal portions lie somewhat inwardly of the blank to assume a position space above the adjacent side walls 20 and 22. The pre-folded distal portions, as described later, are subject to the load of the articles to be placed on such distal portions during the article-loading step and will thereby further folded to reach the respective bracing positions where the distal portions provide part of the respective corner columns.

In either carton-forming process, the distal portion of each side end flap is not glued to, and thereby remains detached from, the adjacent side wall. However, the corner columns are held in their erected tubular forms by means of the articles received in the carton, as will be described in moe details later.

Next, two seperate rows of filled pouches “A” are arranged on the side walls 20, 22 of blank 14 as shown in FIG. 3. The two rows are placed on the side walls 20 and 22 respectively such that each pouch “A” lies on its front or rear panel. It is preferred that the bottoms of the pouches “A” in the left-hand side row as viewed in FIG. 3 face the tops of the pouches “A” in the right-hand side row. It is also preferred that the pouches “A” in each row are arranged one next to another in somewhat overlapping relationship as best illustrated in FIG. 6. The pouches “A” at the ends of each row are placed on the corner columns respectively and thus move and/or hold the distal portions 60 b, 62 b, 64 b and 66 b down in their bracing positions wherein the respective free end edges of the distal portions are pressed against, and thereby frictionally fixed on, the adjacent side walls 20 and 22. The free end edges, therefore, do not require any glue, adhesive or any other securing means (such as staples and adherent tapes) to be attached to the side walls 20, 22 and yet the corner columns are retained in their respective erected tubular forms.

Following the above step, the side walls 20 and 22, are folded toward each other along fold lines 32 and 34 in order to further erect the carton. This is best illustrated in FIG. 4. If desired, mechanical means may be used to help hold the pouches “A” in place during this step. This further erecting step eventually brings the side walls 20, 22 into the upright positions as shown in FIG. 5. When the side walls 20 and 22 are in the upright positions, the pouches “A” in one row become nested with the pouches “A” in the other row in such a manner that the bottoms of the pouches in the one row face the tops of the pouches in the other row. In the carton shown in FIG. 1, the bottoms of the pouches in the left-hand side row and the tops of the pouches in the right-hand side row rest upon the bottom wall 18.

From the condition of FIG. 5, the top wall 24 and the edge flap 80 are folded down to their respective horizontal positions and glued or otherwise secured to each other. The edge flap 80 is hingedly connected to the second side wall 22 along fold line 82. FIG. 1 illustrates the edge flap 80 as being glued to the outside surface of the top wall 24; however, it may alternatively be glued to the inside surface of the top wall 24 depending on the carton-forming process. After the above gluing step, the upper and lower end flaps 56 and 52 are folded downward and upward respectively and glued to the adjacent proximal portions 60 a and 64 a to provide an end closure structure for closing the rear end of the carton. The upper and lower end flaps 58 and 54 are also similarly folded and secured to the adjacent proximal portions 62 a and 66 a to provide the other end closure structure for closing the forward end of the carton. A fully erected carton is thus provided as shown in FIG. 1. In the fully enclosed carton, the pouches “A” occupy a minimum space because the pouches “A” in the one row are nested with those of the other row and also because the pouches in each row are in the overlapping condition.

FIG. 6 is a fragmentary cross-sectional view of the carton of FIG. 1 and shows the condition of the inside of the fully erected carton. As suggested in FIG. 6, the end closure structure at the forward end of the carton is formed from the side end flaps 62 and 66 and the upper and lower end flaps 58 and 54. The distal portions 62 b and 66 b of the side end flaps 62 and 66 extend divergently from the proximal portions 62 a and 66 a toward the side walls 20 and 22 respectively and are held in place against the side walls by pouches “A” so that a front buttress arrangement having the two tubular columns as shown is provided, at least in part, by the front end closure structure. In like manner, the end closure structure at the rear end of the carton is formed from the side end flaps 60 and 64 and the upper and lower end flaps 56 and 52, and thus the rear buttress arrangement that includes the other two triangular tubular columns is provided at least in part by the rear end closure structure. The distal portions 62 b, 66 b; and 60 b, 64 b extend all the way between the top and bottom walls 24 and 18 to allow the front and rear buttress arrangements to enhance the stacking strength of the carton. As viewed in FIG. 1, the fold lines 30, 32, 34 and 82 from the horizontal longitudinal edges of the carton 10 while the transverse fold lines 36 and 38 form the vertical edges and horizontal transverse edges of the carton 10.

As shown in FIGS. 1 and 6, the side end flaps and the upper and lower end flaps at each end of the carton provide the respective end closure structure. Particularly, the distal portions of the side end flaps of each end closure structure extend divergently from the corresponding proximal end portions toward the adjacent side walls. This is best shown in FIG. 6 wherein the distal end portions 62 b and 66 b extend into the internal space of the carton at about 45 degrees with respect to the proximal portions 62 a and 66 a.

Furthermore, the distal portions of each end closure structure extend all the way between the top and bottom walls 24 and 18 and provide a buttress arrangement for enhancing the stacking strength of the carton. The upper and lower ends of each distal portion are in direct abutment on the top and bottom walls 24 and 18 respectively to be able to bear the load transmitted from the top and bottom walls when the carton is arranged with like cartons in a stacked condition.

As shown in FIG. 6, the horizontal transverse size or width W1 (see FIG. 2) of each distal portion (which becomes the hypotenuse of the respective triangular tubular column) is greater than the horizontal transverse size or width of the corresponding proximal portion. This arrangement allows the distal portions to provide the sturdy tubular columns for achieving greater stacking strength. The tubular columns also provide greater structural integrity to the carton 10. Because of the tubular columns, the carton 10 may sustain greater weights when stacked within a group of like cartons.

An alternative method of forming the carton of FIG. 1 is illustrated in FIGS. 7-9. A partially erected carton 12 as shown in FIG. 7 may be formed from the blank 14 of FIG. 2. The various panels, folds, etc have already been described.

In order to form the carton 12, the side end flaps 60, 62, 64 and 66 are folder upward along transverse fold lines 36 and 38 as shown in FIG. 7. Side end flaps 60, 62, 64 and 66 are then folded, or alternatively only pre-folded, along the medial lines 70, 72, 74 and 76 respectively so that the proximal portions 60 a, 62 a, 64 a and 66 a remain perpendicular to the adjacent side walls 20 and 22 and the distal portions 60 b, 62 b, 64 b and 66 b extend inwardly and optionally downward toward the adjacent side walls 20 and 22. As suggested above, the side end flaps may or may not form complete triangular columns at this stage of the carton-forming process.

Next, the top wall 24 is folded upward along the fold line 30, and the upper end flaps 56 and 58 are folded inward and respectively glued to the adjacent proximal portions 60 a and 62 a. The bottom wall 18 is folded upward along the fold line 32, and the lower end flaps 52 and 54 are folded inward and respectively glues to the adjacent proximal portions 60 a and 62 a. This provides the partially fabricated carton 12 as shown in FIG. 7.

Next, two vertically-arranged, seperate rows of filled pouches “A” are placed or loaded, either simultaneously or one row at a time, on side wall 20 as shown in FIGS. 8 and 9. The two rows are placed on the side wall 20 such that each pouch “A” lies with its longer axis extending between the top and bottom walls 24 and 18. It is preferred that the bottoms of the pouches “A” in the upper row face the tops of the pouches “A” in the lower row. However, the bottoms of the pouches “A” in both the rows may face either the top or bottom wall as illustrated in FIG. 9. It is also preferred that the pouches “A” in each row are arranged one next to another in somewhat overlapping relationship, and in particular, that some of the pouches are placed to overlap the distal portions 60 b and 62 b of the side end flaps 60 and 62 at each end of the carton. The pouches A on the distal portions 60 b and 62 b thus move and/or hold the distal portions 60 b and 62 b down in the bracing position to allow the respective triangular columns to be provided by the side end flaps 60 and 62. By this means, the free end edges of the distal portions 60 b and 62 b are pressed against, and thereby frictionally fixed on, the adjacent side walls 20 and 22 but remain detached from the adjacent side walls 20 and 22.

After fully loading the carton as shown in FIG.9, the side panel 22 is folded over along fold line 34 to cover the pouches “A” within the carton. The side end flap 64 is inserted into the carton to place the proximal portion 64 a alongside the inside surfaces of the upper and lower end flaps 56 and 52 while the side end flap 66 is inserted into the carton to place the proximal portion 66 a alongside the inside surfaces of the upper and lower end flaps 58 and 54. By this means, the distal portions 64 b and 66 b are pressed against some of the pouches “A” in the carton and thereby are brought into, and/or retained in, the respective bracing position. The proximal portions 64 a and 66 a are not glued to, and thereby remain detached from, the adjacent upper and lower end flaps while the free end edges of the distal portions 64 b and 66 b are pressed against, but remain detached from, the adjacent side walls 20 and 22. The edge flap 80 is then folded down to and glued or otherwise secured to the outside surface of the top wall 24. After that, a fully erected carton is provided which will also have an appearance as shown in FIG. 1. The carton will be essentially of the same construction as created following the steps shown in FIGS. 3-5. In particualr the carton will have the internal triangular columns for added strength.

A carton of a second embodiment is illustrated in FIG. 10. The carton 90 of FIG. 10 is formed from the blank 13 shown in FIG. 11 and assembles by follwing a further method of forming a carton that is illustrated in FIGS. 12-14. A partially erected carton 11 as shown in FIG. 12 is formed from the blank 13 of FIG. 11. The blank 13 is similar in structure to the blank 14 of FIG. 2. Therefore, the panels, flaps and other parts of the blank 13 similar, if not identical, to those of the blank 14 are designated by like reference numerals, and only the differences will be described herein below in any greater detail.

The proximal portion 64 a and distal portion 64 b of side flap 64 in FIG. 2 have been replaced by a single portion flap 64 c as shown in FIG. 11. Likewise, the proximal portion 66 a and distal portion 66 b of side flap 66 have been replaced by a single portion flap 66 c as shown in FIG. 11. Preferably the transverse dimension W3 of the flaps 64 c and 66 c may be somewhat longer than transverse dimension W2 of the side end flap proximal portions 64 a and 66 a , while still be no greater than the total side-to-side dimension W4 of the finished carton.

The partially erected and fully loaded carton as shown FIG. 14 may be assembled following substantially the same steps as those for forming the partially erected and fully loaded carton of FIG. 9, except the steps of handling the single portion flaps 64 c and 66 c. The single portion flaps 64 c and 66 c may remain unfolded with respect to the side wall 22, and thereby lie in the plane of the side wall 22, until the side wall 22 is folded to the closed position over the pouches “A”. Alternatively, the single portion flaps 64 c and 66 c are merely upwardly pre-folded (as shown in FIG. 14) less then ninety (90) degrees prior to the folding of the side wall 22 to the closed position and prior, more specifically, to the folding of the top and bottom walls 24 and 18 to the respective vertical positions.

After fully loading the carton as shown in FIG. 14, the side panel 22 is folded along fold line 34 to the closed position to cover the pouches “A” within the carton. The single portion flap 64 c is folded about the fold line 36 onto the outside surfaces of the upper and lower end flaps 56 and 52 and is glued thereto while the single portion flap 66 c is folded about the fold line 38 onto the outside surface of the upper and lower end flaps 58 and 54 and is glued thereto. Either prior or subsequent to the folding of the single portion flaps 64 c and 66 c, the edge flap 80 is folded down onto the outisde surface of the top wall 24 and glued, or otherwise secured, thereto. A fully erected carton 90 is thereby provided as shown in FIG. 10. The carton is essentially of the same construction as that of FIG. 1, but the carton 90 include only one (instead of two) internal triangular tubular corner columns at each end of the carton. Stated differently, the end closure structure at each end of the carton 90 provides a buttress arrangement that include only one corner column for added strength.

It will be recognised that as used herein, directional references such as “top”, “bottom”, “base”, “end”, “side”, “inner”, “outer”, “upper”, “lower”, “forward”, and “rear” do not limit the respective panels to such orientation, but merely serve to distinguish these panels from one another. Any reference to hinged connection should not be construed as necessarily referring to a single fold line only: indeed it is envisaged that hinged sonnection can be formed from one or more of one of the following, a sore line, a line of perforation, a line of short slits or their combination, without departing from the scope of invention.

It should be understood that various changes may be made within the scope of the present invention, for example, the size and shape of the panels may be adjusted to accommodate articles of differing size or shape. The carton may accommodate only one or more than two rows of articles. The carton may be provided with one or more removable portions for access to the contents. Also, the pouches contained within the carton, although generally described herein as being in rows or groups with pouch bottoms oriented in a particular direction, may also be placed in various other configurations, such as with every other pouch bottom facing an alternating direction, or in other configurations where some pouches in a row will face one direction and other pouches in a row will face another direction.

The present invention and its preferred embodiment relate to enhancing stacking strength of a fully enclosed carton. It will, however, be apparent and those skilled in the art will recognize that the present invention is capable of many modifications and variations without departing from the scope of the invention. Accordingly, the scope of the present invention is described by the claims appended hereto and supported by the foregoing. 

1. A carton comprising: top and bottom opposed walls hingedly interconnected by a pair of side walls to form a tubular body having an interior; at least one article received in said tubular body; an end closure structure for at least partially closing each of opposite ends of said tubular body; a buttress arrangement provided at least in part by each said end closure structures to enhance the stacking strength of the carton, each of said buttress arrangements including at least one tubular column of a generally triangular cross section, said at least one tubular column being disposed next to said at least one article such that a portion of said at least one tubular column is pressed against one of said side walls and thereby said at least one tubular column is held in an erected tubular form.
 2. The carton of claim 1 wherein said each end closure structure comprises a pair of side end flaps joined to said side walls respectively, each of said side end flaps comprising a proximal portion hingedly connected to a respective one of said side walls and extending toward the other side wall, one of said side end flaps further comprising a distal portion of hingedly connected to said proximal portion of said one side end flap, said distal portion of said one side end flap extending into said interior to form a respective one of said buttress arrangements.
 3. The carton of claim 2 wherein said distal portion of said one side end flap extends all the way between said top and bottom walls to be in abutment at upper and lower ends thereof on said top and bottom walls.
 4. The carton of claim 1 wherein said buttress arrangement at said one end of side tubular body is removable from said carton along with a removable portion to permit said articles to be dispensed from said carton.
 5. The carton of claim 3 wherein said each side end flap includes a vertical fold line dividing said each end flap into said distal and proximal portions, said distal portion having a horizontal transverse size greater than a horizontal transverse size of said proximal portion.
 6. A carton comprising: top and bottom opposed walls hingedly interconnected by a pair of side walls to form a tubular body having an interior; an end closure structure for at least partially closing each of opposite ends of said tubular body; and a buttress arrangement provided by each of said end closure structures, each of said buttress arrangements being disposed within said interior and extending vertically between said top and bottom walls to enhance the stacking strength of said carton, wherein said each end closure structure comprises a pair of side end flaps joined to said side walls respectively, each of said side end flaps of said each end closure structure comprising a proximal portion hingedly connected to a respective one of said side walls, and a distal portion hingedly connected to said proximal portion, said proximal portions extending from said side walls toward each other, said distal portions extending from said proximal portions into said interior and contacting a side wall to form a triangular buttress arrangements, wherein the triangular buttress arrangement is maintained by pressure from the contents of the carton, and wherein said each side end flap includes a vertical fold line dividing said each side end flap into said distal and proximal portions, said distal portion having a horizontal transverse size greater than a horizontal transverse size of said proximal portion.
 7. The carton of claim 6 wherein said respective buttress arrangement is achieved without the use of a glued joint between the end of said distal portion and said contacted side wall.
 8. The carton of claim 7 wherein each of said distal portions of said respective buttress arrangement extends all the way between said top and bottom walls to be in abutment at upper and lower ends thereof on said top and bottom walls.
 9. A method for forming a carton for retaining a plurality of articles, said method comprising the steps of: folding opposed end flaps of each said side wall with respect to the remainder of said blank to respective positions forming triangular buttress arrangements along the inside of the carton at the end and extending from top to bottom of the carton and; and arranging a first row of articles on a first side wall of a blank for forming said carton; arranging a second row of articles on a second side wall of said blank; such that one or more articles lay upon the each said triangular buttress arrangement to help retain its shape; and moving said first and second side walls toward each other such that said articles in said first row are brought into contact with said articles in said second row, whereby Upon closure of the carton the volume of the contents is sufficient to nearly fill the carton and to exert pressure on the inner walls of said triangular buttress to maintain their shape.
 10. The method of claim 9 wherein said end flaps folding step comprises folding each said end flap upward along a first fold line between said each end flap and a respective one of said side walls, and folding said each end flap along a second fold line in said each end flap, said second fold line defining dividing said each end flap into a pair of proximal and distal portions such that said proximal portions of said each side wall extend upwardly from said each side wall and said distal portions of said each side wall extend inwardly from said proximal portions toward a side wall. 